doc/examples/list/cds_list_add_rcu.c

   1 /*
   2  * Copyright (C) 2013  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   3  *
   4  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
   5  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
   6  *
   7  * Permission is hereby granted to use or copy this program for any
   8  * purpose,  provided the above notices are retained on all copies.
   9  * Permission to modify the code and to distribute modified code is
  10  * granted, provided the above notices are retained, and a notice that
  11  * the code was modified is included with the above copyright notice.
  12  *
  13  * This example shows how to add into a linked-list safely against
  14  * concurrent RCU traversals.
  15  */
  16
  17 #include <stdio.h>
  18
  19 #include <urcu/urcu-memb.h>     /* Userspace RCU flavor */
  20 #include <urcu/rculist.h>       /* RCU list */
  21 #include <urcu/compiler.h>      /* For CAA_ARRAY_SIZE */
  22
  23 /*
  24  * Nodes populated into the list.
  25  */
  26 struct mynode {
  27         int value;                      /* Node content */
  28         struct cds_list_head node;      /* Linked-list chaining */
  29 };
  30
  31 int main(void)
  32 {
  33         int values[] = { -5, 42, 36, 24, };
  34         CDS_LIST_HEAD(mylist);          /* Defines an empty list head */
  35         unsigned int i;
  36         int ret = 0;
  37         struct mynode *node;
  38
  39         /*
  40          * Adding nodes to the linked-list. Safe against concurrent
  41          * RCU traversals, require mutual exclusion with list updates.
  42          */
  43         for (i = 0; i < CAA_ARRAY_SIZE(values); i++) {
  44                 node = malloc(sizeof(*node));
  45                 if (!node) {
  46                         ret = -1;
  47                         goto end;
  48                 }
  49                 node->value = values[i];
  50                 cds_list_add_rcu(&node->node, &mylist);
  51         }
  52
  53         /*
  54          * Just show the list content. This is _not_ an RCU-safe
  55          * iteration on the list.
  56          */
  57         printf("mylist content:");
  58         cds_list_for_each_entry(node, &mylist, node) {
  59                 printf(" %d", node->value);
  60         }
  61         printf("\n");
  62 end:
  63         return ret;
  64 }